A desktop Foucalt's pendulum

''Foucalt’s pendulum–a 28 kilogram bob suspended on a 67 metre wire– famously hangs in the Pantheon in Paris where Leon Foucalt himself demonstrated it in 1851.
...
They’ve tested their idea on a 3 metre pendulum and say it works well. They end their paper saying: “We plan to further test this method on even shorter pendula, since there is no lower limit at which the model given here should apply.”'' [source]


And you can even buy one here.